postfix-policyd-spf-perl-2.010/0000775000175000017500000000000011767522637016643 5ustar kittermakittermapostfix-policyd-spf-perl-2.010/CHANGES0000664000175000017500000000765111767522637017647 0ustar kittermakitterma# Legend: # --- = A new release # + = Added a feature (in a backwards compatible way) # ! = Changed something significant, or removed a feature # * = Fixed a bug, or made a minor improvement --- 2.010 2012-06-17 * Fixed incorrect use of != instead of ne for string comparison (LP: #1014243) ! Changed non-standard X-Comment header fields for localhost and whitelisted addresses to use RFC 5451 Authentication Results header fields ! Added depenency on Sys::Hostname::Long for local hostname determination --- 2.009 2012-02-03 * Chomp erroneus NULLs off the end of local and authority explanations to work around a Mail::SPF bug (in Mail::SPF versions prior to 2.008) (LP: #806926) - Patch thanks to Allison Randal * Stop logging queue ID since it is virtually never available and clutters the logs * Reduced non-verbose logging to a single line per message --- 2.008 (2012-01-19 13:46 -0500) ! Query only TXT and not DNS RR Type SPF records to reduce unnecessary DNS lookups (LP: #161133) * Changed default_authority_explanation ('Why' reject text) to point to openspf.net instead of openspf.org due to extended outage * Fix incorrect version string * Ensure all variables are initialized prior to being passed to syslog --- 2.007 (2008-07-25 22:24 -0400) * Update documentation and examples, see Debian bugs 492420 and 492421 for details. --- 2.006 (2008-07-18 00:49 -0400) * Add default logging to make it easier to determine what SPF identity is being used --- 2.005 (2007-12-14 23:29 -0500) * Decreased timeout for DNS queries via UDP to 10s from Net::DNS::Resolver's default of 40s (by doing only 1 retransmission rather than 3 after a query fails). Until Mail::SPF provides an explicit option for this, we just create our own resolver object and make Mail::SPF use that. * Adjust master.cf recommendations in INSTALL for new recommendations from Wietse Venema (postfix-users mailing list). * Other minor documentation cleanup --- 2.004 (2007-04-18 15:36) * Fix header text to work with Postfix (access 5 requirements). --- 2.003 (2007-04-17 08:50) * Minor documentation cleanup. + Add handler for list of relay addresses to bypass. --- 2.002 (2007-02-20 05:45) * Added Julian Mehnle to copyright statement. * Implemented results cache in order to prevent redundant SPF checks in multiple invocations per message instance. This also enables us to prepend a "Received-SPF" header only once per message instance (as opposed to once per recipient address). * Minor code and comments clean-up. --- 2.001 (2007-02-08 00:36) * Safer check for local connections. --- 2.000 (2007-02-07 17:07) * Change reject reply to 550 for RFC 2821 compliance. * Skip SPF checks for local (127.) connections * Clarified wording for some verbose logging. * Added more information about HELO checking to README. --- 1.990 (2007-02-03 16:00) postfix-policyd-spf-perl: ! Changed from Mail::SPF::Query to Mail::SPF for RFC 4408 compliance ! Removed Testing handler (usage was undocumented). ! Removed debian/ dir from release tarball (still provided via SVN). * Simplified logging. Policy server is less chatty. Logs are clearer. --- 1.08.1 (2007-01-10 21:00) postfix-policyd-spf-perl: * Minor and purely cosmetic code clean-up. Miscellaneous: * Updated README file with new website URL and copyright. * Added LICENSE file as an explicit copy of the GPLv2. Debian: * New maintainer: Scott Kitterman * Priority: extra (was: optional) * Removed Build-Depends-Indep: perl, as there really is no need for it. * Depends: libversion-perl * Updated debian/copyright. --- 1.08 (2006-06-17 20:00) * Added Debian package control files. * Moved documentation from executable into separate README and INSTALL files. Improved documentation. * Minor and purely cosmetic code clean-up. # $Id$ # vim:tw=79 sts=2 sw=2 postfix-policyd-spf-perl-2.010/INSTALL0000664000175000017500000000222611767522637017676 0ustar kittermakittermaSystem Requirements ------------------- The following Perl version and packages are required for running postfix-policyd-spf-perl: Perl 5.6 version NetAddr-IP 4 Mail::SPF (not Mail-SPF-Query) version 2.006 or later Sys::Hostname::Long Installing ---------- 1. Copy postfix-policyd-spf-perl to /usr/local/lib/policyd-spf-perl 2. Add the following to /etc/postfix/master.cf: policy unix - n n - 0 spawn user=nobody argv=/usr/local/lib/policyd-spf-perl 3. Configure the Postfix policy service in /etc/postfix/main.cf: smtpd_recipient_restrictions = ... reject_unauth_destination check_policy_service unix:private/policy ... NOTES: Specify check_policy_service AFTER reject_unauth_destination or else your system can become an open relay. The user 'nobody' is used in this example. This is appropriate if you do not have any other services running as nobody. If you do, create a dedicated user for this service and use it instead. 4. Add "policy_time_limit = 3600" to main.cf 5. Restart Postfix. postfix-policyd-spf-perl-2.010/postfix-policyd-spf-perl0000775000175000017500000003200011767522637023447 0ustar kittermakitterma#!/usr/bin/perl # postfix-policyd-spf-perl # http://www.openspf.org/Software # version 2.010 # # (C) 2007-2008,2012 Scott Kitterman # (C) 2012 Allison Randal # (C) 2007 Julian Mehnle # (C) 2003-2004 Meng Weng Wong # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License along # with this program; if not, write to the Free Software Foundation, Inc., # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. use version; our $VERSION = qv('2.010'); use strict; use IO::Handle; use Sys::Syslog qw(:DEFAULT setlogsock); use NetAddr::IP; use Mail::SPF; use Sys::Hostname::Long 'hostname_long'; # ---------------------------------------------------------- # configuration # ---------------------------------------------------------- my $resolver = Net::DNS::Resolver->new( retrans => 5, # Net::DNS::Resolver default: 5 retry => 2, # Net::DNS::Resolver default: 4 # Makes for a total timeout for UDP queries of 5s * 2 = 10s. ); # query_rr_type_all will query both type TXT and type SPF. This upstream # default is changed due to there being essentiall no type SPF deployment. my $spf_server = Mail::SPF::Server->new( dns_resolver => $resolver, query_rr_types => Mail::SPF::Server->query_rr_type_txt, default_authority_explanation => 'Please see http://www.openspf.net/Why?s=%{_scope};id=%{S};ip=%{C};r=%{R}' ); # Adding more handlers is easy: my @HANDLERS = ( { name => 'exempt_localhost', code => \&exempt_localhost }, { name => 'exempt_relay', code => \&exempt_relay }, { name => 'sender_policy_framework', code => \&sender_policy_framework } ); my $VERBOSE = 0; my $DEFAULT_RESPONSE = 'DUNNO'; # # Syslogging options for verbose mode and for fatal errors. # NOTE: comment out the $syslog_socktype line if syslogging does not # work on your system. # my $syslog_socktype = 'unix'; # inet, unix, stream, console my $syslog_facility = 'mail'; my $syslog_options = 'pid'; my $syslog_ident = 'postfix/policy-spf'; use constant localhost_addresses => map( NetAddr::IP->new($_), qw( 127.0.0.0/8 ::ffff:127.0.0.0/104 ::1 ) ); # Does Postfix ever say "client_address=::ffff:"? use constant relay_addresses => map( NetAddr::IP->new($_), qw( ) ); # add addresses to qw ( ) above separated by spaces using CIDR notation. # Fully qualified hostname, if available, for use in authentication results # headers now provided by the localhost and whitelist checks. my $host = hostname_long; my %results_cache; # by message instance # ---------------------------------------------------------- # initialization # ---------------------------------------------------------- # # Log an error and abort. # sub fatal_exit { syslog(err => "fatal_exit: @_"); syslog(warning => "fatal_exit: @_"); syslog(info => "fatal_exit: @_"); die("fatal: @_"); } # # Unbuffer standard output. # STDOUT->autoflush(1); # # This process runs as a daemon, so it can't log to a terminal. Use # syslog so that people can actually see our messages. # setlogsock($syslog_socktype); openlog($syslog_ident, $syslog_options, $syslog_facility); # ---------------------------------------------------------- # main # ---------------------------------------------------------- # # Receive a bunch of attributes, evaluate the policy, send the result. # my %attr; while () { chomp; if (/=/) { my ($key, $value) =split (/=/, $_, 2); $attr{$key} = $value; next; } elsif (length) { syslog(warning => sprintf("warning: ignoring garbage: %.100s", $_)); next; } if ($VERBOSE) { for (sort keys %attr) { syslog(debug => "Attribute: %s=%s", $_ || '', $attr{$_} || ''); } }; my $message_instance = $attr{instance}; my $cache = defined($message_instance) ? $results_cache{$message_instance} ||= {} : {}; my $action = $DEFAULT_RESPONSE; foreach my $handler (@HANDLERS) { my $handler_name = $handler->{name}; my $handler_code = $handler->{code}; my $response = $handler_code->(attr => \%attr, cache => $cache); if ($VERBOSE) { syslog(debug => "handler %s: %s", $handler_name || '', $response || ''); }; # Pick whatever response is not 'DUNNO' if ($response and $response !~ /^DUNNO/i) { if ($VERBOSE) { syslog(info => "handler %s: is decisive.", $handler_name || ''); } $action = $response; last; } } syslog(info => "Policy action=%s", $action || ''); STDOUT->print("action=$action\n\n"); %attr = (); } # ---------------------------------------------------------- # handler: localhost exemption # ---------------------------------------------------------- sub exempt_localhost { my %options = @_; my $attr = $options{attr}; if ($attr->{client_address} ne '') { my $client_address = NetAddr::IP->new($attr->{client_address}); return "PREPEND Authentication-Results: $host; none (SPF not checked for localhost)" if grep($_->contains($client_address), localhost_addresses); }; return 'DUNNO'; } # ---------------------------------------------------------- # handler: relay exemption # ---------------------------------------------------------- sub exempt_relay { my %options = @_; my $attr = $options{attr}; if ($attr->{client_address} ne '') { my $client_address = NetAddr::IP->new($attr->{client_address}); return "PREPEND Authentication-Results: $host; none (SPF not checked for whitelisted relay)" if grep($_->contains($client_address), relay_addresses); }; return 'DUNNO'; } # ---------------------------------------------------------- # handler: SPF # ---------------------------------------------------------- sub sender_policy_framework { my %options = @_; my $attr = $options{attr}; my $cache = $options{cache}; # ------------------------------------------------------------------------- # Always do HELO check first. If no HELO policy, it's only one lookup. # This avoids the need to do any MAIL FROM processing for null sender. # ------------------------------------------------------------------------- my $helo_result = $cache->{helo_result}; if (not defined($helo_result)) { # No HELO result has been cached from earlier checks on this message. my $helo_request = eval { Mail::SPF::Request->new( scope => 'helo', identity => $attr->{helo_name}, ip_address => $attr->{client_address} ); }; if ($@) { # An unexpected error occurred during request creation, # probably due to invalid input data! my $errmsg = $@; $errmsg = $errmsg->text if UNIVERSAL::isa($@, 'Mail::SPF::Exception'); if ($VERBOSE) { syslog( info => "HELO check failed - Mail::SPF->new(%s, %s, %s) failed: %s", $attr->{client_address} || '', $attr->{sender} || '', $attr->{helo_name} || '', $errmsg || '' ); }; return; } $helo_result = $cache->{helo_result} = $spf_server->process($helo_request); } my $helo_result_code = $helo_result->code; # 'pass', 'fail', etc. my $helo_local_exp = nullchomp($helo_result->local_explanation); my $helo_authority_exp = nullchomp($helo_result->authority_explanation) if $helo_result->is_code('fail'); my $helo_spf_header = $helo_result->received_spf_header; if ($VERBOSE) { syslog( info => "SPF %s: HELO/EHLO: %s, IP Address: %s, Recipient: %s", $helo_result || '', $attr->{helo_name} || '', $attr->{client_address} || '', $attr->{recipient} || '' ); }; # Reject on HELO fail. Defer on HELO temperror if message would otherwise # be accepted. Use the HELO result and return for null sender. if ($helo_result->is_code('fail')) { if ($VERBOSE) { syslog( info => "SPF %s: HELO/EHLO: %s", $helo_result || '', $attr->{helo_name} || '' ); }; return "550 $helo_authority_exp"; } elsif ($helo_result->is_code('temperror')) { if ($VERBOSE) { syslog( info => "SPF %s: HELO/EHLO: %s", $helo_result || '', $attr->{helo_name} || '' ); }; return "DEFER_IF_PERMIT SPF-Result=$helo_local_exp"; } elsif ($attr->{sender} eq '') { if ($VERBOSE) { syslog( info => "SPF %s: HELO/EHLO (Null Sender): %s", $helo_result || '', $attr->{helo_name} || '' ); }; return "PREPEND $helo_spf_header" unless $cache->{added_spf_header}++; } # ------------------------------------------------------------------------- # Do MAIL FROM check (as HELO did not give a definitive result) # ------------------------------------------------------------------------- my $mfrom_result = $cache->{mfrom_result}; if (not defined($mfrom_result)) { # No MAIL FROM result has been cached from earlier checks on this message. my $mfrom_request = eval { Mail::SPF::Request->new( scope => 'mfrom', identity => $attr->{sender}, ip_address => $attr->{client_address}, helo_identity => $attr->{helo_name} # for %{h} macro expansion ); }; if ($@) { # An unexpected error occurred during request creation, # probably due to invalid input data! my $errmsg = $@; $errmsg = $errmsg->text if UNIVERSAL::isa($@, 'Mail::SPF::Exception'); if ($VERBOSE) { syslog( info => "Mail From (sender) check failed - Mail::SPF->new(%s, %s, %s) failed: %s", $attr->{client_address} || '', $attr->{sender} || '', $attr->{helo_name} || '', $errmsg || '' ); }; return; } $mfrom_result = $cache->{mfrom_result} = $spf_server->process($mfrom_request); } my $mfrom_result_code = $mfrom_result->code; # 'pass', 'fail', etc. my $mfrom_local_exp = nullchomp($mfrom_result->local_explanation); my $mfrom_authority_exp = nullchomp($mfrom_result->authority_explanation) if $mfrom_result->is_code('fail'); my $mfrom_spf_header = $mfrom_result->received_spf_header; if ($VERBOSE) { syslog( info => "SPF %s: Envelope-from: %s, IP Address: %s, Recipient: %s", $mfrom_result || '', $attr->{sender} || '', $attr->{client_address} || '', $attr->{recipient} || '' ); }; # Same approach as HELO.... if ($VERBOSE) { syslog( info => "SPF %s: Envelope-from: %s", $mfrom_result || '', $attr->{sender} || '' ); }; if ($mfrom_result->is_code('fail')) { return "550 $mfrom_authority_exp"; } elsif ($mfrom_result->is_code('temperror')) { return "DEFER_IF_PERMIT SPF-Result=$mfrom_local_exp"; } else { return "PREPEND $mfrom_spf_header" unless $cache->{added_spf_header}++; } return; } # ---------------------------------------------------------- # utility, string cleaning # ---------------------------------------------------------- sub nullchomp { my $value = shift; # Remove one or more null characters from the # end of the input. $value =~ s/\0+$//; return $value; } postfix-policyd-spf-perl-2.010/README0000664000175000017500000001004611767522637017524 0ustar kittermakittermapostfix-policyd-spf-perl 2.010 A Postfix SMTPd policy server for SPF checking (C) 2007-2008,2012 Scott Kitterman (C) 2012 Allison Randal (C) 2007 Julian Mehnle (C) 2003-2004 Meng Weng Wong Thanks for contributions by various members of the SPF project ============================================================================== postfix-policyd-spf-perl is a Postfix SMTPd policy server for SPF checking. It is implemented in pure Perl and uses the Mail::SPF CPAN module. Note that Mail::SPF is a complete re-implementation of SPF based on the final SPF RFC, RFC 4408. It shares no code with the older Mail::SPF::Query that was the original SPF development implementation. If you are upgrading from on older (<< 2.000) version of this policy server you will need to install Mail::SPF. At least version 2.006 of Mail::SPF is required. This version of the policy server always checks HELO before Mail From (older versions just checked HELO if Mail From was null). It will reject mail that fails either Mail From or HELO SPF checks. It will defer mail if there is a temporary SPF error and the message would othersise be permitted (DEFER_IF_PERMIT). If the HELO check produces a REJECT/DEFER result, Mail From will not be checked. If the message is not rejected or deferred, the policy server will PREPEND the appropriate SPF Received header. If Mail From is anything other than completely empty (i.e. <>) then the Mail From result will be used for SPF Received (e.g. Mail From None even if HELO is Pass). The policy server skips SPF checks for connections from the localhost (127.) and instead prepends and logs 'SPF skipped - localhost is always allowed.' If you have relays that you want to skip SPF checks for, you can add them to relay_addresses on line 78 using standard CIDR notation in a space separated list. For these addresses, 'X-Comment: SPF skipped for whitelisted relay' is prepended and logged. IPv6 localhost is also skipped. Error conditions within the policy server (that don't result in a crash) or from Mail::SPF will return DUNNO. See INSTALL for installation instructions. Usage: policyd-spf-perl [-v] This documentation assumes you have read Postfix's README_FILES/ SMTPD_POLICY_README. Logging is sent to syslogd. Each time a Postfix SMTP server process is started it connects to the policy service socket, and Postfix runs one instance of this Perl script. By default, a Postfix SMTP server process terminates after 100 seconds of idle time, or after serving 100 clients. Thus, the cost of starting this Perl script is smoothed out over time. The default policy_time_limit is 1000 seconds. This may be too short for some SMTP transactions to complete. As recommended in SMTPD_POLICY_README, this should be extended to 3600 seconds. To do so, set "policy_time_limit = 3600" in /etc/postfix/main.cf. Testing the policy daemon ------------------------- To test the policy daemon by hand, execute: % /usr/local/lib/policyd-spf-perl Each query is a bunch of attributes. Order does not matter, and the daemon uses only a few of all the attributes shown below: request=smtpd_access_policy protocol_state=RCPT protocol_name=SMTP helo_name=some.domain.tld queue_id= instance=71b0.45e2f5f1.d4da1.0 sender=foo@bar.tld recipient=bar@foo.tld client_address=1.2.3.4 client_name=another.domain.tld [empty line] The policy daemon will answer in the same style, with an attribute list followed by a empty line: action=550 Please see http://www.openspf.org/Why?id=foo@bar.tld&ip=1.2.3.4& receiver=bar@foo.tld [empty line] To test HELO checking sender should be empty: sender= ... More attributes... [empty line] If you want more detail in the system logs change $VERBOSE to 1. License ------- postfix-policyd-spf-perl is free software. You may use, modify, and distribute it under the GNU GPL (version 2 or later); see the LICENSE file. postfix-policyd-spf-perl-2.010/LICENSE0000664000175000017500000004310311767522637017651 0ustar kittermakitterma GNU GENERAL PUBLIC LICENSE Version 2, June 1991 Copyright (C) 1989, 1991 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Lesser General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow. GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you". Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does. 1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. 2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions: a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change. b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License. c) If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.) These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it. Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program. In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. 3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following: a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.) The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable. If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code. 4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it. 6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License. 7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program. If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances. It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice. This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License. 8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License. 9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. 10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. END OF TERMS AND CONDITIONS How to Apply These Terms to Your New Programs If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. Copyright (C) This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: Gnomovision version 69, Copyright (C) year name of author Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers) written by James Hacker. , 1 April 1989 Ty Coon, President of Vice This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License.